a. 缺乏表情的, 未能表达原意的

[ adj ]
deliberately impassive in manner
<adj.all>
deadpan humorhis face remained expressionless as the verdict was read

Unexpressive \Un`ex*press"ive\, a.
1. Not expressive; not having the power of utterance;
inexpressive.

2. Incapable of being expressed; inexpressible; unutterable;
ineffable. [Obs.]

Run, run, Orlando; carve on every tree
The fair, the chaste and unexpressive she. --Shak.
※ -- {Un`ex*press"ive*ly}, adv.